Estimation of severity of illness with APACHE II: age-related implications in cardiac arrest outcomes

The ability to predict outcomes of cardiac arrest before starting cardiopulmonary resuscitation (CPR) would be useful for discussions of resuscitation with elders and their families. We thought CPR outcome might be dependent on the severity of pre-existing illnesses. The APACHE II is a severity-of-illness (SOI) scale based, in part, on physiologic parameters whereby points are given for degree of deviation from normal. Additionally, up to six points are given for increased age. We hypothesized that (1) patients with the highest APACHE II would be least likely to survive, and (2) because of the blunted physiologic responsiveness, the APACHE II would underestimate the SOI of elderly patients who were sufficiently ill to have a cardiac arrest. A retrospective study of 172 arrests was carried out to evaluate these hypotheses. For the young cohort (n = 126; age, < 70; mean age, 59 ± 8), mean admission APACHE II was 16.5 ± 7.9 and pre-arrest APACHE II was 20.8 ± 8.9. For the old cohort (n = 46; age, ≥ 70; mean age, 76 ± 7) admission APACHE II was 17.0 ± 5.8 (NS) and the pre-arrest APACHE II was 20.3 ± 6.5 (NS). Logistic regression analysis was carried out with both APACHE II scores and factors previously correlated with CPR outcome. Witnessed arrests and those requiring a low number of medications were most likely to result in immediate success (restoration of blood pressure) and in a live discharge. APACHE II score (24 h pre-arrest) was associated with live discharge in the regression analysis. We conclude the pre-arrest APACHE II does add modestly to the ability to predict outcomes of CPR efforts and measures SOI equally well in young and old cohorts.